Research On Optimization Of Dynamic Railcar-flow Assignment And Classification Track Assignment In Marshalling Yard

Marshalling yards play as important nodes to collect and distribute railcar-flow in railway freight transportation network,where inbound railcar-flows are humped and assembled to generate planned outbound flows.In the daily routine of marshalling yard,the organization and operation are conducted under the guide of yard operation plan.As the important component of the plan,receiving and departure tracks assignment plan,engines utilization plan and railcar-flow assignment plan are called stage plan as a whole.And the problem of engines utilization and railcar-flow assignment is called dynamic railcar-flow assignment in domestic theoretical study.Therefore,a reasonable and effective stage plan is important to coordinate the organization of yard staff and the utilization of yard equipment,and speed up railcars transfer process.To complete the shunting task,a shunting plan should be made under the constraints of the given stage plan.Classification tracks assignment,the core context of shunting plan,is of highly connection with the dynamic railcar-flow assignment plan,considering a scenario that the stage plan cannot be conducted due to the poor capacity of classification tracks.Moreover,it is of theoretical value and application significance to consider classification tracks assignment while studying the problem of dynamic railcar-flow assignment.This thesis aims to study the problem of marshalling yard dynamic railcar-flow assignment with the consideration of classification tracks assignment.Firstly,the research in the field of dynamic railcar-flow assignment and classification tracks assignment is reviewed.And then,the yard operation organization is analyzed from the aspects both of decision-making process and practical operation process.Specifically,the sorting strategies and the relationship between dynamic railcar-flow assignment and classification tracks assignment are introduced.After that,a programming model is developed to optimize dynamic railcar flow assignment and classification track assignment,aiming at maximizing outbound railcar number over the planning horizon,and subjecting to the constrains of train humping and assembling jobs,railcar-flow assignment and classification track number and capacity.It is concluded that the problem is NP-Hard.To meet the efficiency demand of decision-making,an approximation algorithm is proposed to solve the model.A numerical experiment is conducted to valid the proposed model and algorithm.At last,this thesis adopts the up-bound humping-assembling system in Fengtai West Marshalling Station as case study,and uses the data collected in practical operation process to valid the model and algorithm furtherly.